D.12 Upgrading from 3.1.x to 4.0

Starting from the version 4.0, MFL no longer uses the
predefined symbolic names for exception codes (previous versions used
the ‘&’ prefix to dereference them). Instead, it relies on
constants defined in the include file status.mfh
(see status.mf).

However, the script files from 3.1 series will still work, but
the following warning messages will be displayed:

Another important difference is that pragmatic options ‘ehlo’
and ‘mailfromd’ are now deprecated, as well as their command line
equivalents --ehlo and --domain. These options
became superfluous after the introduction of mailfrom_address
and ehlo_domain built-in variables. For compatibility with the
previous versions, they are still supported by mailfromd
4.0, but a warning message is issued if they are used: